1. Field of Invention:
This invention relates generally to roof flashings to ensure a tight roof construction, and more particularly to a flashing unit which is adapted to be marginally telescoped into a like unit whereby a series of such units in overlapping relation may be installed on an upstanding wall at its intersection with the roof.
2. Status of Prior Art:
The purpose of roof flashing, which is installed at the intersection of a roof and a parapet, curb or other upstanding wall is to ensure a tight roof construction, for in the absence of flashing, water may leak into the junction between the roof and the wall. In order to render a roof watertight, a common practice is to use roofing felt whose end is turned up to bear against the face of the upstanding wall, a metal flashing of copper or other material being then applied to occupy the angle between the roof and the wall.
In the Hobbs U.S. Pat. No. 1,992,123, the metal flashing includes an upwardly extending flange section covering the upturned end of the roof felt which bears against the wall, and an outwardly extending base section which covers the portion of the roofing felt applied to the roof. Between the flange and the base section of the metal flashing is a sealing strip created by a fold in the metal to form a pocket between it and the base section of the flashing. Inserted in this pocket is the edge of a sheet of roofing material. The practical drawback to the Hobbs arrangement is that while the flashings can be installed in edge to edge relation to form a longitudinal series of flashings along the wall, the flashings are not watertight at their abutting edges. Moreover, it is not watertight along corners unless special fittings are provided, or the metal flashings are soldered together at their edges, which is, a costly and time consuming procedure.
The Wilson U.S. Pat. No. 2,057,285, discloses a metal flashing which may be nailed onto a concrete wall and which includes a trough adapted to receive a plastic sealing material. This flashing is not easily workable around corners.
The Griffiths U.S. Pat. No. 1,105,422, discloses a metal counter flashing which is bent upon itself to provide a wing and a holding loop, a canvas base flashing being pinched between the loop and the wing. A flashing which combines metal and textile components is impractical and expensive under current conditions, and doesn't lend itself readily to the longitudinal interconnection of flashings.
The Theriault U.S. Pat. No. 3,698,143, discloses a flashing sheet bent into a V-shape for disposition on a shingle and against the side to be flashed, the sheet having a portion that is inserted under the top edge of the shingle. This is essentially a base flashing and requires an excessive amount of labor to install.